Field of the Invention
The present invention relates to a transmission structure of a hybrid electric vehicle (HEV), and more particularly, to a transmission structure of an HEV for improving fuel efficiency by allowing a power split driving and a parallel driving in the hybrid vehicle and for allowing a driving mode to be switched depending on various driving situations.
Description of Related Art
In general, a hybrid vehicle, which is a vehicle driven by a combination of electrical power and a power source of an internal combustion engine, is controlled so as to be operated at a point of high efficiency of a system by a gasoline engine and an electrical motor to thereby efficiently reduce exhaust gas while having excellent efficiency.
In addition, since the hybrid vehicle does not need to build a separate charging facility such as an electric vehicle and may improve fuel efficiency and secure the same driving distance as that of an existing gasoline vehicle, it is expected to form a key point of the future of an eco-friendly car.
In this case, a power branch method of the hybrid vehicle includes a mechanical flow in which power of the engine is directly transferred to an output shaft using a power branch apparatus that branches a power flow such as planetary gear and an electrical flow in which a generator is driven using the power of the engine. In this case, a battery is charged with the generated power or a motor is driven by energy of the charged battery.
However, hybrid vehicles according to the related art have decreased efficiency upon driving, which results in deterioration of fuel efficiency.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.